Electrolytic condenser and method of operating the same.



E. D. MERSHON. ELECTROLYTIC CONDENSER AND METHOD OF OPEIIATING THE SAME.

APPLICATION FILED JAN. 4, 1910.

Patented Mar. 23

2 SHBBTSSHEET 1.

R. D. MBRSHON. ELECTROLYTIC CONDENSER AND METHOD OF OPERATING THE SAME.

APPLICATION FILED JAIL L, 1910 Patented Mar. 23, 1915;

2 SHEETS-SHEET 2.

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RALPH n MERSHON, 01' NEW YORK, N.

ELECTROLYTIC CONDENSER AND METHOD OF OPERATING THE SAME.

Specification of Letters Patent.

Patented Mar. 23,- 1915 Application filed January 4, 1919. Serial No.536,355.

To allwkom it may concern:

Be it known that I RALPH D- MERsHoN, residing at New York, in the countyand State of New York, have invented certain new and useful Improvementsin Electrolytic Condensers and Methods of Operating the Same, of whichthe following is a full, clear, and exact description.

In my copending application Ser. No. SQ $8M, filed October 27, 1909, Ihave pointed out that the action of the so-called electrolytic condenserdepends, for high effigration of the plates, and, of course, great lossof elliciency in the operation of the condenser. In the applicationmentioned I have also described, and claimed broadly, an invention inwhich this electrolyte charge is supplied or maintained by auxiliaryexciting means, so that, as there is no appreciable diminution of suchcharge, flow of current from the electrolyte to the electrodes isprevented or reduced to a negligible amount.

My present invention is in the nature of an improvement in the above,and will be readily understood from the subjoined description of severalconvenient and effective embodiments.

In the annexed drawings, Figure l illustrates diagrammatically one formof the invention described and claimed broadly in my prior applicationreferred truancl is in its essential features the same as that shown inFig. 7 of said prior application, being introduced here for convenienceor". description. Figs. 2, 3, 4, and 5 show diagranp matically severaleffective cmlmdimcnts of my present invention.

The electrolytic condenser shown in I 1 comprises a tank M. containing asuitable electrolyte N. tor example a solution oi bm'nX. sodium orammonium phosphate. citric acid, or other suitable chemical, and

two or more electrodes as A, A, of alu nnnum or other film-formingmetal. Inimersed in the electrolyte is a non-filming electrode C, ofcarbon or other suitable material, connected to the negative pole of abattery B, the positive pole of which is con;

'nected tothe middle point of an auto-transformer T. The terminals ofthe latter are connected to the supply leads L, L, which are alsoconnected to the condenser electrodes A, A, respectively.

From the principle involved in both electrolytic rectifiers andcondensers, namely, that current can fiow from the electrolyte.

to the film-coated electrodes with little or no opposition but isstrongly opposed in the other direction, it will be seen that when analternating E M. F., single phase in the present case, is impressed uponthe device through the supply leads from a suitable source of current,S, a unidirectional E. M. F. will be produced between the terminals Qand D, tending to produce a unidirectional current in the direction ofthe arrow between these points. This 13. M. F. is opposed, however, bythe battery voltage, so that so long as the latter voltage is just equalto the former no current can flow either to or from the battery; but itthere should occur any leakage of the negative charge of theelectrolyte, which would re sult in diminishing the difference ofpotential between 0 and I), current will flow from the battery to thecondenser in sulficient amount to replace the charge or the part of thecharge so lost. The battery thus constitutes an auxiliary excitingmeans. and its use as described obviates the necessity or possibility ofperforation and consequent deterioration of the condenser films. Toinsure this result with certainty the voltage of the battery should. beslightly in excess of that produced between 0 and I) by the alternatingcurrent impressed upon the apparatus. than that between 0 and D currentwill flow across these points and charge the battery. which would ofcourse mean current flowing from the electrode C to the plates A, A, andperforation of the films thereon.

To guard against this contingency an elec tric valve of any well knowntype may be inserted in circuit with the battery to provcut flow ofcurrent from the condenser to the battcry.

It the battery E. M. F. be less 100 A convenient type oi valve is shownat V, comprising a. non-filming electrode C and a film-coated electrodeA immersed in a suitable electrolyte, the firstnamed electrode beingconnected to the terminal D and the other to the negative pole of thebattery.

After the condenser has been put in operation the only function of theexciter (in Fig. 1 the battery B) is to I maintain the negative chargein the electrolyte, that is, to compensate for any leakage that mayoccur through the films or over insulation, which function will ofcourse require only a small amount of current from the exciter. But ifthe condenser should stand idle for some time, with the exciterdisconnected or inactive, the charge may leak away in whole or in largepart, and in such case if the con denser and exciter be simultaneouslyswitched on to the supply circuit the exciter must, in a quarter cycleor less, furnish such portion of the necessary electrolyte charge as ismissing. If this portion is not supplied by the exciter it will beinitially supplied from the supply circuit, with perforation of one ormore of the films on the condenser electrodes. This possibility may beavoided by leaving the exciter operatively in circuit with the condenserat all times, which would mean continued expenditure of power, and

hence waste, when the condenser is not in use; or, by making the exciterof sutlicient capacity to bring the electrolyte charge up to normal in aquarter cycle or less, which would mean an exciter of larger capacitythan is necessary in steady operation.

As both the above methods are disadvantageous in the respects mentionedI prefer to secure the desired normal excitation by switching theexciter into circuit with the condenser before the latter is operativelyconnected up with the supply leads, so as to insure complete restorationof the electrolyte charge by the exciter before the current from thesupply leads is operatively impressed on the condenser. This method ofoperating the condenser, and the means for practising the same, form thesubject of my present application.

Various means may be employed for making the connections in the sequenceor order described above. For example, in Fig. 2, which is otherwiseidentical with Fig. 1 and answers to the same description, I have shownsimple switches S, S, in the supply leads L, L, and the exciter leads I,I, respectively. In this construction,-when the condenser is to be putinto operation the switches S are closed first and the exciter allowedto bring the excitation up to normal, after which the switches S areclosed. The exciter circuit need be closed only a few cycles ahead ofthe condenser circuit to insure full excitation, and hence the intervalof time required will in general be very small, a fraction of a secondbeing amply sufiicient in any case unless the capacity of the exciter berelatively quite small.

In the arrangement shown in Fig. 3 the exciting current is supplied bythe main source of current through the instrumentality of theauto-transformer T and the exciter R, the latter being a smallelectrolytic rectifier consisting of a non-filming elec-- trode C andtwo film-coated electrodes A, A in a suitable electrolyte. The'leads Z Zto the condenser electrodes A, A are connected to switches S both ofwhich may be brought into connection with a tap 2? from the middlepointof the transformer. The supply leads L L containing switches S areconnected to taps t, 2?, brought out from the transformer, which alsohas taps F, 25 27', from points intermediate to t and t on oppositesides of the latter, as shown. The electrodes A, A of the-exciter areconnected to the transformer terminals by leads Z Z In this arrangementtheswitches S are closed and switches S are thrown to the innercontacts, on tap t. Unidirectional charging current is thus supplied tothe condenser, and after a suitable interval the switches or controllersS are thrown to taps 6 then to 25 and finally'to t. In this Way the maincircuit is established through the condenser and the source of currentby a series of steps, putting morev and more voltage on the condenseruntil the full line voltage is impressed, but of course the connectioncan be made by a single step if desired. An analogous arrangement isillustrated in Fig. 4, except that the filmeoated exciter electrodes A Aare in the same tank as the condenser electrodes A A", the mode ofoperation to elfect the preliminary charging of the condenser being thesame as in the case of Fig. 3. Instead of several switches a singleswitch, for example one of the controller type, may be used as in Fig.5. In this construction position 1 of the controller J closes thecircuit through the supply leads L L and the auto-transformer T. Inposition 2 the tap 6* from the middle point of the transformer isconnected to the condenser electrodes A A. In position 3 the condenserelectrodes are connected to taps t and in position 4 they are connectedto taps t" and thus have higher voltage impressed on them. Finally, inposition 5 the condenser electrodes are connected directly to the supplyleads L, L and hence receive the full line voltage. The exciterelectrodes A A are connected to the transformer terminals throughout theabove steps, as in the arrangement previously described.

It will be observed that in Figs. 3, 4, and 5 the condenser electrodesare at times shortcircuited, it being thus possible to employ a singleauto-transformer instead of two.

" This short circuit can do no harm if the connection is insulated fromthe electrolyte;

and in that case the only efiect is to equalize between the electrodessuch charge as the condenser may already have. If, in addition, theshort circuit connection is made to the middle point of the transformerand the exciter is connected to the supply leads the charge alreadypossessed by the condenser will be increased, if it were below normalvalue, by the exciter E. M. F. If the exciter is not active theshort-circuit connection is still insulated from the electrolyte to theextent of the films on the exciter electrodes.

In practice it will usually erable to provide in connection with thecontroller of Fig. 5 suitable means for preventing too quick movement ofthe controller from position 2 to position 3, so as to insure ample timefor the preliminary excitation of the condenser. Similarly, the switchesin Figs. 2, 3, and 4 may be interlocked or otherwise constructed in suchmanner as to make their operation impossible except in the propersequence and with suflicient time-interval between. Inasmuch asinstrumentalities for such purposes are well known it is deemedunnecessary to illustrate any specific examples of the same herein.

The constructions illustrated herein are, as previously stated,effective and convenient embodiments of the invention, which may beembodied in other forms without departure from its proper spirit andscope.

I claim:

1. The combination of an electrolytic condenser, auxiliary exciting means therefor, a

source of current, means for opening and closing the circuit between theexciting means and the condenser, and step-by-step means for closing thecircuit between the condenser and the said source.

. '2. The combination of an electrolytic condenser, auxiliary excitingmeans therefor, a

source of current, a transformer connected to the condenser through saidexciting means, and a controller connected with the transformer andhaving a plurality of positions in one of whichthe source of current isconnected to the condenser through the exciting means and in another ofwhich the main circuit is established through the condenser and saidsource. be found pref- 3. The combination of an electrolytic condenser,auxiliary exciting means therefor, a

source 'of current, a transformer connected to the exciting means, and acontroller for connecting the transformer and condenser to said source,said controller being constructed to connect the exciting means to thecondenser in one position of the controller and in succeeding positionsto impress higher and higher voltage on the condenser.

4. The combination of an electrolytic condenser, a source of alternatingcurrent, means for deriving unidirectional charging current from thesource to excite the condenser, and a controller between the source andthe condenser and arranged to connect the exciting means to thecondenser to excite the same in advance of closing the circuit betweenthe source and the condenser.

In testimony whereof I ai'lixv my signature in the presence of twosubscribing witnesses.

I RALPH D. MERSHON.

\Vitnesses M. LAWSON DYER, S. S. DUNHAM.

